BootStrap

Bootstrap is the most popular HTML, CSS, and JavaScript framework for developing responsive, mobile-first websites, and it is completely free to download and use!

Bootstrap is an HTML, CSS, and JS library that focuses on simplifying the development of informative web pages, as opposed to web applications. The primary purpose of adding it to a web project is to apply Bootstrap's choices of color, size, font, and layout to that project. Therefore, the primary factor is whether the developers in charge find those choices to their liking. Once added to a project, Bootstrap provides basic style definitions for all HTML elements, resulting in a uniform appearance for prose, tables, and form elements across web browsers. In addition, developers can take advantage of CSS classes defined in Bootstrap to further customize the appearance of their content. For example, Bootstrap has provisions for light- and dark-colored tables, page headings, more prominent pull quotes, and highlighted text.